Dramatic increase in methane in the Arctic in January 2013http://apocadocs.com/s.pl?1360007126
... Sea ice is declining at exponential pace. The big danger is that a huge rise of temperatures in the Arctic will destabilize huge amounts of methane currently held in the seabed. Comprehensive and effective action is needed now to avoid catastrophe....
As said, there appears to be a strong relationship between the location of the high levels of methane and the contours of land and sea ice, as illustrated by the above animation. There appears to be little relationship between methane levels and depth of the sea, as illustrated by the animation on the right.